In rotary printing techniques wherein a paper web, a plastic web or some other substrate is printed with a pattern, the need often arises for interim checking of the printing performance or, possibly, the repeat printing pattern. In rotary printing installations where the printed web is fed into a folding or cutting station after the last processing station, such checking is feasible at the end of the installation.
The interconnection of stations for printing, drying, cutting and folding of a web in one continuous operation imposes, however, limitations as to the speed of the printing machine due to the cutting and folding operation. Placing such an installation into operation furthermore is time consuming. Consequently, there is a demand for a rotary printing installation in which the printed web, after having passed through the drying apparatus, advances to a receiving station having winding rollers without the need for folding or cutting of the web, i.e., so that the speed of the printing machine is not unnecessarily limited.
It is therefore an object of the present invention to enable a sample to be taken in such an installation without interrupting its continuous operation. The invention comprehends a device for taking such a sample from a continuously supplied printed web which is, during sampling, discharged continuously to a receiving station.